Traditionally, U-shaped spring clips used with pivot shafts for visors have tended to produce a second, unwanted detent position oriented approximately 180.degree. from the intended visor storage (retracted) position. This is due to the presence of two sides, or legs of the clip which press against opposite sides of the pivot shaft. A flat surface on the shaft, by necessity, engages first one leg and then the other as the visor is rotated about the shaft. Various modifications have been tried to minimize this second or double detent position. Most of these attempts fall into one of two categories.
The first category utilizes a clip with legs of different widths as measured in the direction of the axis of rotation. One of the legs is narrower than the flat surface on the shaft and is designed to fully engage the flat surface to provide a detent position. The other leg is wider than the flat surface and is not intended to engage the flat surface because both ends of the leg are held up away from the flat surface as they travel continuously on the cylindrical portions of the shaft outboard of the flat surface at opposite ends thereof. The center portion of the wider leg is intended to bridge the flat surface of the shaft, thereby avoiding engagement with the flat surface.
In practice, the wider leg does not bridge straight across the flat surface. Rather, it has a tendency to be distorted and bow or sag slightly as it bridges across the flat surface due to a strong inward acting clamping force of the clip. Even a slight amount of distortion causes the wider leg to come into contact with the edges of the flat surface causing a second, and often a third, unwanted detent position.
U.S. Pat. No. 4,785,500 to Langridge discloses a hinge assembly for vehicle accessories. In this configuration, one leg of the clip is wider than the other, relying on the wider arm to span the flat surface on the pivot arm. In this configuration, a second dent position will result for the reasons set forth above.
The second category or alternative approach to spring clips, is to have one or both legs incorporate openings, cut-aways or recessed areas. The pivot shaft is designed to have a flat surface which is interrupted by lobes (areas where there is not flat surface). When such a clip is in its detent position, these lobes align with the openings in the clip allowing the leg (or legs) of the clip to engage the flat surface. When rotated approximately 180.degree., from its detent position, the leg (or legs) of the clip are held out away from the flat surface by the lobes. The intent is to prevent the leg (or legs) of the clip from engaging the flat surface to avoid the unwanted second detent position.
In practice, such designs are not successful, because the inward clamping force of the clip causes the leg (or legs) to distort or bow inwards slightly at either end of the lobe. This distortion allows portions of the leg to contact the edges of the flat surface causing one or possibly two extra detent positions.
A secondary problem with clips of this category, is that the openings weaken the clip, thereby reducing the effectiveness of the clip in maintaining the rotational position of the visor. This in turn reduces the life expectancy of the clip due to earlier fatigue failure.
An example of this type of clip appears in U.S. Pat. No. 4,617,699 to Nakamura which discloses a hinge structure for a visor or the like which features a single storage position snap action function. The U-shaped clip provides recesses to receive lobes on the pivot shaft when in the detent position. As discussed above, such an approach results in the second detent position.
U.S. Pat. Nos. 4,925,232 and 5,071,186 to Hemmeke et al., disclose a visor having a mounting bracket utilizing openings in the legs of the clip cooperating with lobes on the pivot shaft. In this configuration, a double detent position is not eliminated as discussed above.
U.S Pat. No. 4,394,043 to Moulding et al., discloses a visor and a mounting bracket having a longitudinally extending shaft. A mounting clip is connected to the visor which includes a leaf spring which exerts a radial force on the shaft to resist radial and axial movement. This design utilizes a clip with a single protrusion which corresponds to a single annular groove on the pivot shaft. In this configuration, the annular groove and protrusion are intended to prevent axial movement of the clip relative the pivot shaft. They do not prevent the leg from contacting the flat on the pivot shaft. This clip eliminated a second detent position by utilizing only one leg. However, by not being U-shaped (i.e. having 2-legs), this design is subject to early fatigue-cracking due to its inherent uneven distribution of stresses.
U.S. Pat. No. 4,841,599 to Cebollero discloses a spring mechanism for the hinge of a motor-vehicle visor having two different embodiments. In one embodiment, the pivot shaft does not have a flat surface and correspondingly no detent positions exist. Another embodiment teaches two flat surfaces on the pivot shaft with two corresponding detent positions.
U.S. Pat. No. 4,821,374 to Gavagan discloses a hinge assembly for a vehicle visor and other vehicle accessories. A clip is disclosed which relies on a leaf spring to exert pressure against one side of the pivot shaft. In this configuration, a plurality of flat surfaces are provided on the pivot shaft to obtain a corresponding number of detent positions.
U.S. Pat. No. 4,582,356 to Kaiser et al., discloses a pivot bearing for use with a visor for automotive vehicles. In this configuration, the clip is designed to slide axially along the pivot shaft. No attempt is made to eliminate the second detent position.
U.S. Pat. No. 4,057,287 to Lilja discloses a sun shade for a motor vehicle having a clip utilizing three longitudinally arranged sleeves in axial alignment. The center sleeve is slightly misaligned to provide friction against the pivot shaft. One embodiment utilizes a flat surface to provide a single detent position. This design does not provide the high detent-retention force of a U-shaped clip.
The present invention is directed to improving known mounting systems for use with visors for vehicles.